The effects of pharmacological interventions in current clinical use (nitroglycerin, propranolol) and in experimental trial (diltiazem) on the natural revascularization, coronary flow distribution and regional myocardial mechanics following acute ligation of the left anterior descending artery in conscious instrumented pigs. Pigs, unlike dogs, lack significant pre-existing collateral coronary vessels as does man. Evaluation of myocardial blood flow by 15 mu radionuclide-labeled spheres, myocardial regional contractile patterns and derived region work in normal perischemic and ischemic regions will be made. Determination of the efficacy of pharmacological intervention on border zone mechanics and blood flow in regions as far as 2 cm from the sharp ischemic margin will lead to increasing understanding of the relationships between regional myocardial contractile performance and local blood flow during the acute and sustained phases of coronary artery occlusion.